Ventilation grille



FIG. 1 is a perspective view of the ventilation grille.

FIG. 2 is bottom view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a front view thereof; and,

FIG. 6 is a rear view thereof.

The broken line showing of parts of the drawings depicts use and environment and forms no part of the claimed design. 

The ornamental design for a ventilation grille, as shown and described. 